An Iranian diplomat held hostage in Yemen since 2013 returned home to Tehran on Thursday amid conflicting accounts of how he was freed from his unidentified abductors.

IRNA, Iran's state news agency, quoted deputy foreign minister Hossein Amir Abdollahian as saying that an Iranian intelligence operation in Yemen rescued Noor Ahmad Nikbakht, an administrative official at Tehran's embassy in Sanaa.

Iran's state-run Press TV showed Nikbakht looking healthy and wearing a suit when he met his family and Abdollahian on arrival at Tehran airport.

But Yemeni media run by the Iran-backed Houthi group that controls Sanaa told a different story, saying the diplomat was freed in a prisoner exchange that took place in another country.

Nikbakht was the second high-profile hostage freed in Yemen this week. A Saudi Arabian diplomat seized in 2012 was released on Monday after being held by al Qaeda in the Arabian Peninsula.

Iran's Abdollahian told IRNA that "a special team from the Intelligence Ministry was able to free Nikbakht from the clutches of terrorists in a series of complex and difficult operations in a very particular part of Yemen."

IRNA quoted Intelligence Minister Mahmoud Alavi as saying that Iran secured Nikbakht's release "without accepting any of the terrorists' demands and at minimal cost".

But a security source at the Yemeni Interior Ministry, which is run by the Houthi group, told the Saba news agency that the diplomat was exchanged in an operation outside of Yemen.

"No security operations were carried out on Yemeni territory. The operation was in another country, where a group of terrorists were held," the agency said, saying Nikbakht was exchanged for "elements seized outside the state".

Yemen's al-Masserah TV, also run by the Houthi group, said a leader of the Islamic State in Iraq had been exchanged for the diplomat. The report gave no further details.

Yemen has plunged deeper into turmoil since the Iranian-backed Shi'ite Muslim Houthi group seized control of the capital in September last year.

Reuters